1. Field of the Invention
The present invention is related to data communications. In particular, the present invention is related to a method and apparatus for multicasting data packets in a meshed topology network.
2. Description of the Related Art
Simultaneously, or nearly simultaneously, sending a data packet from a source node to multiple destination nodes may be accomplished by multicasting. Multicasting provides point to multipoint delivery of a data packet to nodes that statically or dynamically choose to receive the data packet Generally, multicasting utilizes a special destination hardware address recognized by a group of destination nodes. In a meshed topology network, a source node is likely connected to a destination node via multiple paths, each defined by a unique combination of switches, or routers, and point to point connections. The switches/routers implement software, firmware, or the like, that stores and forwards multicast data packets. Thus, multicasting generally results in a destination node that chooses to be a member of the multicast group receiving multiple copies of a multicast data packet sent to the multicast group, one for each unique path between the source node and the destination node in the network.
Today, as the size of internetworks grows, and as the amount of point-to-multipoint, or multipoint-to-multipoint communications across internetworks grows, the management of multicast data traffic is an increasingly important issue. In the case of bridged local area networks, the Institute of Electrical and Electronic Engineers (IEEE) standardized on a distributed algorithm and protocol for a spanning tree to control the routing of data packets across network segments, as set forth in section 4 of ANSI/IEEE standard 802.1D for Media Access Control (MAC) bridging. The IEEE standard eliminated the problem of multiple copies of the same data packet being forwarded to or over a particular network segment. However, the standard also required that each node in the network maintain information regarding the state of the spanning tree as well, which introduced the need for recovery procedures every time the state changed, and caused delay in the operation of the internetwork. A change in internetwork topology required recalculation of the network connectivity graph, as well as the relearning of addresses and forwarding tables at each of the bridges in the internetwork. This reconvergence takes time, during which data packets are not transmitted across the internetwork. What is needed is a different multicast data packet forwarding paradigm that does not rely on the spanning tree algorithm and protocol. Moreover, what is needed is a model for forwarding multicast data traffic that transcends IEEE local area networks to other networks such as satellite-, radio-, Signaling System 7 (SS7), cellular-, packet switched-, wide area-, asynchronous data cell-, and other types of networks.